1. Field of the Invention
The present invention relates generally to a system for compressing and decompressing data contained in a micro-bar code which is much smaller than typically used bar codes. More specifically, the invention relates to a micro-bar code data processing system which can reduce the number of digits of data by compressing data to be contained in the bar code and thus shortening the length of the bar code required for expressing the data.
2. Description of the Related Art
As is well known, a bar code is designed to encode information, such as various characters, such as letters, figures, signs by the combination of a plurality of solid bars arranged in a mutually parallel relationship to one another and blank intervals between the bars (which will be hereafter referred to as white bars). The following four types of bar codes are typically used.
(1) JAN (Japanese Article Number) Code
This coding system has been used for the identification of consumer goods produced in Japan. The JAN coding system is compatible with UPC (Universal Product Code) system used in the United States and the EAN (European Article Number) system used in Europe and Asia. In the JAN coding system, 13 digits of standard code and 8 digits of compressed code are available. The standard JAN code consists of 2 digits of a country code, 5 digits of a product maker code, 5 digits of a product item code and 1 check digit. The compressed code has essentially the same code format as the standard code but has 4 digits of the product maker code and 1 digit of the product item code. In the JAN coding system, only FIGS. 0.multidot.9 can be expressed by the combination of the solid bars and white bars. This coding system is convenient for reading since it is not sensitive to the scanning direction of a bar code reader.
(2) ITF (Interleaved Two of Five) Code
The coding system is a standard coding system adapted to physical distribution, which is established by adding a physical distribution identification code of 1 or 3 digits (including 1 leading digit which is normally a 0) to the foregoing JAN code. Therefore, this ITF code may express only FIGS. 0.about.9. This coding system is successfully used in the field of transportation. In addition, this coding system is employed as data for timed recording of a video tape recorder (VCR). The ITF coding system features a high recording density and a stable information reading precision level even when the bar code is printed on a printing medium having poor printing conditions.
(3) CODE 39
In this coding system, one character is expressed by 9 bars (4 white bars between 5 solid bars). Among 9 bars, 3 bars are thick solid or white bars having greater width. As start and stop codes, an asterisk (*) is employed. This coding system permits one to express FIGS. 0.about.9, alphabetic letters of A.about.Z, various signs (e.g., +, -, blank space, /, $, %, .). This coding system has been employed a standard in industrial fields for factory automation. The system used AIAG in the United States automobile industry, and the HIBC system used in United States hospitals and pharmaceutical the industry are well known examples of this type of coding system.
(4) NW-7 (CODABAR)
In this coding system, one character is expressed by 7 bars (3 white hams between 4 solid bars). Among seven bars, 2 or 3 bars are thicker bars. As start and stop codes, one of A, B, C and D is used. This coding system is capable of expressing FIGS. 0.about.9 and various signs (e.g., +, -, /, $, :, .).
In recent years, there have been developed technologies for printing bar codes on various media with substantially high precision and to read such bar codes. According to progress of the technology, the so-called micro-bar code, which is much smaller than typical available bar codes, is coming into practical use. The most thin black bar constituting the micro-bar code is 100 .mu.m in width and about 1.about.10 mm in length. Since such micro-bar bar codes can be placed in a space which is too small to put the conventional normal size bar codes, there are various plans to use such micro-bar codes as media for transmission of information in various fields in addition to the physical distribution which has been the primary to of use of the bar codes.
For instance, by indicating a names of manufacturers, article code numbers and production dates of goods on a catalog for remote ordering, the consumers may exactly order the desired goods by reading the information contained in the micro-bar codes by means of a bar code reader system without causing error. Such an arrangement would be particularly useful when the bar code reader system is coupled with other information transmission systems, such as a communication terminal. The micro-bar code representing specific information unique to each article can be considered as a group of bar codes of a necessary number of digits for expressing individual information associated with the article, such as the name of the manufactures or so forth. Therefore, for representing a greater amount of information a , longer length of the micro-bar code is naturally required. Here, it should be noted that throughout the disclosure, the length of the bar code represents a dimension in a direction perpendicular to the black bars from the leading edge of the leading black bar to the trailing edge of the rear end black bar.
on the other hand, in view of reading of the micro-bar code printed on a variation of surfaces such as a newspaper, paperboard or so forth, by means of the bar code reader system, it is desirable to make the width of the black bars as well as the white bars as wide as possible so as to avoid reading error or failure of reading due to printing errors, e.g., blotting, scratching of the ink or so forth. In other words, this means that by containing the information included in the conventional normal size bar code in the micro-bar code, the space for displaying the information can be remarkable reduced, while the precision of reading of the information can be degraded under a condition where the printing quality can fluctuate. Accordingly, it is strongly desired to shorten the length of the micro-bar code without reducing the information to be contained therein. This may be achieved by reducing number of digits to be expressed by the micro-bar code.